516 OPHIDIANS. 



into the stomach ; the shell, as well as its contents, subserving 

 the purposes of food. 



SECOND FAMILY. Boida. BOAS AND PYTHONS. 



This family includes species which, although not venomous, 

 are exceedingly terrific on account of their gigantic size and 

 amazing strength. In these, the ventral shields are narrow, 

 transverse, and often six sided ; the pupil is oblong and erect, 

 excepting in the genus Tortrix. But perhaps the most marked 

 peculiarity, is their possession, contrary to the general rule in 

 serpents, of hooked. like claws, connected internally with a 

 series of bones, representing, though imperfectly, those of the 

 lower limbs. The tail is prehensile, and can be firmly twined 

 around any object. The Boas are natives of South America ; 

 the Pythons of Asia and South Africa. Some serpents, kindred 

 to these, are also seen in Australia. 



Imagination finds it difficult to picture more formidable objects 

 than the reptiles of this group ; and yet, if we can credit the 

 statements of ancient writers, serpents far more terrific than these, 

 were once found in the Eastern Continent. Livy refers to one 

 which "had its lair on the banks of the Bagradas, near Utica, 

 and swallowed many of the Roman soldiers in the army of 

 Regulus," and which was finally killed by stones discharged from 

 military engines. The skin, afterwards taken to Rome by 

 Regulus, it is said, "measured one hundred and twenty -three 

 feet ! " This, however, may be an exaggeration, or the term 

 " feet," is, perhaps, to be understood in a more limited sense than 

 that which we assign to it. 



The Boas, properly so called, sometimes reach the length of 

 forty feet. In their entwining folds, acting with the combined 

 energy of thousands of muscles for crushing their victims, they 

 possess a power which no man or animal can successfully resist. 

 To climb, to swim, to dart along the ground, are endowments of 

 these powerful reptiles, and they avail themselves of each as 

 occasion requires. 



In the Boas, the head is covered with small scales to the muz- 

 zle ; and the scuta of the tail are undivided. In the Pythons, 

 there are plates over the anterior part of the head, and the 

 scuta of the tail are divided. 



The EMPEROR BOA, Boa constrictor, (see fig. on Chart,) is 

 characterised by a broad chain extending along the back, and 

 consisting alternately, of large, blackish, and somewhat hexa- 

 gonal marks, and of pale, oval dashes or spots. The epithet 



